The invention relates to adhesives for textiles. More particularly, it relates to aqueous polyurethane bonding adhesives for laminating and flocking textile materials.
Laminating involves the bonding of fabrics, both synthetic and natural, either to one another or to other plastic materials to form a multilayer product. Flocking involves the bonding of short, cut fibers in a perpendicular position to a substrate to form a pile-like material.
As indicated above, laminating in the textile field means the bonding of a fabric to the same or different fabric or fabrics or the bonding of one or more fabrics to plastic materials, including films, sheetings, and foams.
A discussion of the background in the area of adhesives, is given in U.S. Pat. No. 3,640,924, and in the related commonly assigned, copending applications, Ser. Nos. 184,609; 184,610; 275,392; and 275,393; filed respectively Sept. 28, 1971; Sept. 28, 1971; July 26, 1972; and July 26, 1972.
Adhesive compositions in the textile field are applied both as flocking and laminating adhesives. In the present invention, the primary application is for flocking applications although other uses include bonding applications for laminates.
The adhesives used in textile laminating and flocking should provide products having (1) dimensional stability to washing, dry cleaning and pressing, (2) durability of the bond between the components to washing, dry cleaning and pressing and (3) satisfactory handle and drape characteristics. In the apparel field, resistance to dry cleaning and/or laundering are important, but is is particularly important that the flocked garment have a soft hand. Furthermore, the adhesive composition must be applicable by the conventional methods for applying adhesive to fabrics, or plastics materials, as by doctor blade technique or by using a plain or gravure transfer roll. The adhesive should be sufficiently viscous to prevent penetration into the fabric or foam. It should be flexible, even when fully cured, and should not become brittle on aging. Although many of the adhesives currently used have a solvent base, aqueous base adhesives are desirable since (1) they can be diluted with water for cleaning purposes, (2) they do not present a fire or explosive hazard, (3) they have less odor and are nontoxic and (4) present no air pollution problems.
The general disclosure of U.S. Pat. No. 3,640,924 which is hereby incorporated by reference, discloses a method for preparing a textile adhesive composition wherein an isocyanate-terminated prepolymer is converted into a latex by stirring it in an aqueous medium containing a tertiary lower alkylamine, allowing chain extension with water to proceed until substantially all of the isocyanate groups have reacted and adding a thickening agent to the latex to adjust the viscosity from 20,000 to 100,000 cps. This composition is useful in flocking processes, however, it cannot be used to make flocked fabrics because textile materials thus obtained have a boardy hand.
Other pertinent prior art references are U.S. Pat. Nos. 3,388,087 and 3,412,054.